To prevent noise or the like which occurs in electronic circuits, and to maintain a steady function of semiconductor IC equipment and the like, a capacitor such as a bypass capacitor or a decoupling capacitor is connected between signal terminals and ground circuits, or between power-source terminals and ground circuits of a semiconductor IC component. Also, an interposer made of a silicon substrate is used, for example, between a semiconductor chip and a wiring substrate, or used as a relay substrate to form interlayer interconnections in a semiconductor chip. Technology to form the above-mentioned capacitor in an interposer has been already developed.
For example, a method to form a capacitor on a silicon substrate is described in Published Patent Application 2001-508948 (WO98/32166). The technology to manufacture a silicon capacitor is described in Published Patent Application 2001-508948 as follows: A hole structure is formed in a silicon substrate; a conductive zone is formed by doping the substrate surface, and a dielectric layer and a conductive layer are deposited on the surface without filling the hole structure; also, to offset the mechanical strain on the silicon substrate affected by the doping of the conductive zone, a conformal auxiliary layer under compressive mechanical stress is formed on the surface of the conductive layer.
Conventionally, in a silicon capacitor, capacitor capacitance is expanded by using a trench structure to enlarge the surface. To form capacitors, processes such as CVD or sol-gel methods have been used on interposer surfaces or trenches.
However, in a method in which a silicon capacitor is manufactured by forming a trench structure in a silicon substrate, it is expected that the dielectric in the capacitor will absorb moisture during the manufacturing process of the capacitor, and the leakage of electric current will expand. Furthermore, when the capacitor is installed in a circuit package, potential electric shortages may occur between capacitor electrodes due to the absorbed moisture in the dielectric.
To minimize the circuit package height, an interposer is laminated on a support substrate and then sanded. After the interposer is mounted on the circuit substrate, a step to exfoliate the support substrate is employed. In a conventional capacitor, when a solution treatment is applied to exfoliate the support substrate from the interposer, potential degradation of the electrical characteristics of the capacitor may occur due to solution seepage into the dielectric or bond residue.